Photographic sensitizer



Patented July 7, 1942 PHOTOGRAPHIC SENSITIZER Gustav Oskar Riester,Dessau,

Wilmanns, Wolfen,

Kreis Bitterfeld, and Karl Kumetat,

Wolfen, Kreis Bitterfeld, Germany, assignors, by mesne assignments, toGeneral Aniline & Film Corporation, New York, N. Y., a corporation ofDelaware No Drawing. Application October 12, 1938, Serial No. 234,604.In Germany October 18, 1937 3 Claims.

Our present invention relates to photographic sensitizers.

There is a series of sensitizers comprising particularly members of thecyanine-group which serve to sensitize silver halide emulsions for greenand green-yellow; that is to say, they are orthochromatic sensitizers.In order to be able to use the brightest light possible in processingthe sensitized material in the dark-room, the spectral composition ofthe light in the darkroom must be shifted as far as possible towards theshort wave lengths, i. e. towards bright red or orange. The limit is seton this condition by the initial sensitivity of the emulsion to certainwave lengths. If the sensitizing curve rises from yellow or yellowgreenvery gradually and flatly, the intensity of the spectral sensitivity atthese wave lengths is practically of no importance in working exposures,for it amounts only to a fraction of the intensity of the sensitivity atthe sensitizing maximum. This small sensitivity sulfices, however, tofog the emulsion when the light of the darkroom falls within thatspectral region. Such emulsions, therefore, can only be worked up withcorrespondingly longer Wave lengths, that is to say with lightphysiologically darker. If, however, a sensitizer is used thesensitizing curve of which falls away as strongly as possible towardsthe long wave lengths, or a generally more selective sensitizer, thespectral composition of the light in the darkroom may be nearer to thesensitizing zone. Similar advantages of a highly selective sensitizingoccur when there is a gap in the green, in which case the processing isconducted in green light.

It is one object of our invention to provide ortho-chromatic emulsionshaving sensitizing curves which fall away steeply and also havepronounced definite and limited positions of the sensitizing region.

A further object is the provision of trimethinecyanines containing atleast one benzimidazole ring.

A still further object is to provide trimethinecyanines with abenzimidazole ring which contains at the nitrogen atoms alkyl, aralkylor aryl groups.

Other objects of our invention will appear from the descriptionfollowing hereinafter.

The new sensitizers have the following general formula:

A f A T ]I C'-CH=CHCH=C\ i B N/ 1 B xit R2 in which:

Y=O, S, Se, CH=CH, or

R1=alkyl,

R2=alkyl, aryl, aralkyl or acetoxyalkyl X=acid radical, such as Cl, Br,I, S04, C104 or para-toluene sulfonate,

A,B=hydrogen, alkyl or aryl, A and B together may also representunsubstituted or substituted aryl of the benzene series.

For the production of the unsymmetrical dyestuffs one starts fromheterocyclic w-aldehydes, that is to say an aldehyde in which thealdehyde group is asubs'tituent in a methine group attached in2-position to the nitrogen atom; for example benzthiazole-,benzselenazole-, benzoxazole-, or trimethylindoline 2 methine-w-aldehydemay be used, This (ll-aldehyde is caused to react with 1 mol of2-methyl-N,N-dialkyl(arylalkyl) -benzimidazolium halide in the presenceof a condensing agent, for example pyridine and piperidine.

The dyestulf may contain substituents in the 40 benzene ring. Thebenzene ring of the benzimidazole may carry a fused-on benzene ring.

The dyestufi is incorporated with the emulsion especially in an'emulsion ripened with the use of ammonia emulsion or with the finishedlayer in any usual manner.

methine-w-aldehyde and 1.3-diethyl-2-methyl-6- ethoxybenzimidazoliumiodide and corresponding with the following formula sensitizes a silverbromide emulsion in the green with a maximum at 570 ma with a very steepfalling-away of the sensitivity curve towards the region of long waves.

Example 2.The dyestuif produced from 1.1.3-trimethyl-G-methoxyindoline-Z-methine-w aldehyde and1.3-diethyl-2-methyl 6 ethoxybenz imidazolium iodide and correspondingwith the following formula sensitizes a silver halide emulsion in thegreen with a maximum at 545 m and without a gap in the green.

Example 3.-The dyestuff obtained by means of1.1.S-trimethyl-6-methoxyindoline2-methinew-aldehyde and1-ethyl-2-methyl-3-phenyl-benzimidazolium iodide and corresponding tothe following formula:

sensitizes without a gap in the green and with a maximum at 560 mExample 4.-The dyestufi obtained from 1.1.3-trimethylindoline-2-methine-w-aldehyde and 1-ethyl-2-methyl-3-phenyl-benzimidazolium iodide has the followingformula:

and sensitizes without a gap in the green and with a maximum at 540 mExample 5.The dyestufi produced by means of3-ethyl-benzselenazole-Z-methine-w-aIdehyde and1-ethyl-2-methyl-3-phenyl-benzimidazolium ethyl sulfate andcorresponding to the following formula:

zHs 5 sensitizes to about 585 m without a gap and with a maximum at 557m Example 6.The unsymmetrical dyestuff obtained from3-ethyl-benzselenazole-2-methinew-aldehyde and1-ethyl-2-methyl-3-phenyl-6 chloro-benzimidazolium ethyl sulfate andhaving the following composition:

sensitizes to about 600 m with a maximum at 567 my Example 7.-Theunsymmetrical dyestuff obtained from3-ethyl-benzthiazole-2-methine-waldehyde andl-ethyl-2-methyl-3-phenyl-benzimidazolium ethyl sulfate and having theformula:

CzHn

2 5 CnHs sensitizes to 585 m witha'maximum at 555 my.

Example 8.The dyestuff produced. from 3-ethyl-benzthiazole-2-methine-w-aldehyde and 1- ethyl-2-methyl-3-phenyl 6chlorobenzimidazolium ethyl sulfate and having the formula:

CzHs I 0 l sensitizes to 550 m with a maximum at 525 m Example 10.Thetrimethinecyanine from 3 ethyl-5.13 naphthoxazole-Z-methine-wealdehydeand 1-ethyl-2-methyl-3-phenyl-6-chloro-benzimidazolium ethyl sulfate hasthe formula:

and sensitizes to 560 m with a maximum at 538 m Example 11.The dyestuiffrom 1.1.3-trimethylindoline-2-methine-w-aldehyde and 1- ethyl 2methyl-3-(4-bromophenyl) -6-chloro benzimidazolium ethyl sulfate has theformula and sensitizes to 5'75 m l with a maximum at 580 m Example12.-The dyestuff obtained by means of l".1.3-trimethyl-indoline 2methine-w-aldehyde and 1-eth'yl-2-methyl-3(4'-methoxyphenyD-benzimidazolium ethyl sulfate has the following formulaand sensitizes to 565 m with a maximum at 540.

Example 13.-The dyestuff from1.1.3-trimethylindoline-2-methine-w-aldehyde and 1- ethyl-Z-methyl3-phenyl 6 chloro benzimidazolium-ethyl sulfate has the formula andsensitizes to 580 m l with a maximum at 550.

Example 14.-The dyestufi obtained from 1.1.3 trimethylindoline 2methine-w-aldehyde and 1ethYl-2-methyl;3 -phenyl 5.6dichlorobenzimidazolium ethyl sulfate and corresponding with thefollowing formula sensitizes to 590 m with a maximum at 560 m Example15.--The trimethinecyanine obtained from 1.1.3trimethylindoline-2-methine-w-aldehyde and1-ethyl-2.5-dimethyl-3-phenyl-benzimidazolium ethyl sulfate andcorresponding with the formula sensitizes to 565 ml with a maximum at540 mp.

Example 16.--The trimethinecyanine produced by means of1.1.3-trimethylindo1ine-2-methinew-aldehyde and1-ethyl-2-methyl-3-phenyl-6 trifluoromethyl-benzimidazolium ethylsulfate and corresponding with the formula:

CH3 CH3 sensitizes to 570 m with a maximum at 542 m Example 18.Thetrimethinecyanine obtained from N-ethyl-thiazoline-2-methineu-a1dehydeand! 1-ethy1-2-methyl-3-phenyl-6-chloro-ben3zimidazolium ethyl sulfateand having the formula C2115 CaHs sensitizes with a maximum at 510 mExample 19.The trimethinecyanine produced from1.1v.3-trimethylindoline-2-methine-w-aldehyde and1-ethyl-2-methy1-3-acetoxy-propyl-6- chloro-benzimidazolium ethylsulfate and having the following structural formula sensitizes to 570 mwith a maximum at 545 m Example 20.--The trimethinecyanine produced fromN-ethyl-thiazoline-2-methine-w-aldehyde, and1-ethyl-2-methyl-3-acetoxypropyl-6-chlorobenzimidazolium ethyl sulfatehas the following structural formula and sensitizes with a maximum at503 mp.

Example 21 .--The trimethinecyanine produced from1.2-dimethyl-3-acetoxypropyl-6-oh1orobenzimidazolium methyl sulfate andN-ethyl-benzselenazole-2-methine-w-aldehyde having the following formulaI Se I Cl 'CH=CH-CH=C I 021:, on, x-

CH2 $H2 O.CO.CH:

and sensitizing to 590 ml with a maximum at Example 22.Thetrimethinecyanine produced from1-ethyl-2-methyl-3-acet0xypropyl-6-ch1orobenzimidazolium-ethyl sulfateand N-ethyl- 555 III/1..

Example 23.The trimethinecyanine produced from1-ethyl-2-methyl-3-phenyl-6-chlorobenzimidazolium ethyl sulfate andN-ethyl-quinoline-2-methine-w-aldehyde has the following formula andsensitizes to 650 m with a maximum at 600 m and a gap at 500 m Example24.-The trimethinecyanine produced from1-ethyl-2-methy1-3-pheny1-benzimidazolium-ethyl sulfate and N-ethyl-5.6-dimethylbenzselenazole-2-methine-w-aldehyde has the followingformula C 2H5 I N H3C- Se JZ'CH=CHCH=C 7 I I CgHs CtHs and sensitizes to590 m with a maximum at 563 m Example 25.The trimethinecyanine producedfrom 1-ethyl-2-methyl-S-phenyl-G-chlorobenzimidazolium-ethyl sulfate andN-ethyl-5.6-dimethylbenzselenazole-2-methine-w-aldehyde has thefollowing formula and sensitizes to 610 m with a maximum at 575 mExample 26.--The trimethinecyanine produced from1-ethyl-2-methyl-3-phenyl-benzimidazo1ium-ethyl sulfate andN-ethyl-5-methoxy-benzselenazole-2-methine-w-aldehyde has the followingformula and sensitizes to 600 m with a maximum at 565 ma.

Example 27.--The trimethinecyanine produced from1-ethyl-2-methyl-3-phenyl-6-chlorobenzimidazolium-ethyl sulfate andN-ethyl-5-methoxy benzselenazole 2 methine-w-aldehyde has the followingformula and. sensitizes to 610 m with a maximum at 575 m l,

Example 28.The trimethinecyanine produced froml-ethyl-2-methyl-3-phenyl-6-chloro-benzimidazolium ethyl sulfate and1.1.3-trimethyl-6- methoxy-indoline-2-methine-w-aldehyde has thefollowing formula and sensitizes to 600 nm with a maximum at 570 my.

Example 29.-The trimethinecyanine produced from1-ethyl-2-methyl-3-pheny1-6-chloro-benzimidazolium ethyl sulfate and1.1.3.6-tetramethylindQIine-Z-methine-w-aldehyde has the followingformula and sensitizes to 590 m with a maximum at 558 mp" Example30.-The trimethinecyanine produced from 1.2dimethyl-3-phenyl-6-chlorobenzimidazolium-methylsulfate and1.1.3-trimethyl-indoline-2-methine-w-aldehyde has the following formulaand sensitizes to 580 m with a maximum at 550 Ina.

Example 31.The trimethinecyanine produced from 1-ethyl-2-methyl-3-(4'-ch1orophenyl) benzimidazolium ethyl sulfate and1.1.3-trimethylindoline-2-methine-w-aldehyde has the following formuladuced from 1-ethyl-2-methyl-3-(4'-chloropheny1-)-benzimidazoliumethy1sulfate and. 1.1.3.6- tetramethyl-2-methine-w-aldehyde has the followingformula and sensitizes to 575 m with a maximum at 548 Example 33.Thetrimethine cyam'ne produced from 1 -ethyl-2-methyl-3- (4-ch1oropheny1-)benzimidazolium ethyl sulfate and N ethyl-thiazoline-Z-methine-w-aldehyde has the following formula and sensitizes from 450to 510 m with a maximum at 493 mp.

Example 34.The trimethinecyanine produced from l-ethyl-Z-m e t h y 1-3-(4'-chlorophenyl-) benzimidazolium ethyl sulfate and. Nethyl-5.6-dimethyl benzselenazole-2-methine-w-aldehyde has the following formulaand sensitizes to 600 mu with amaximum at 565 Example 35 .Thetrimethinecyanine produced from 1 -ethyl-2-methyl-3- (4'-methoxyphenyl-)benzimidazolium-ethyl sulfate and N-methyl5.6

dimethyl benzselenazole-Z-methine-w-aldehyde has the following formula IOCHa Example 36.--The trimethinecyanine produced from1-propy1-2-methyl-3-phenyl-6-chlor0benzimidazoliumiodide and1.1.3-trimethyl-indoline- Z-methine-w-aIdehyde has the following formulaand sensitizes to 580 my with a maximum at 550 Example 37.-Thetrimethinecyanine produced from1-ethy1-2-methyl-3-phenyl-6-chloro-benzimidazolium-ethyl sulfate andN-propyl-Ll-dimethyl-indoline-Z-methine-w aldehyde has the followingformula CH3 CzHa CaH1 6 5 and. sensitizes to 580 ma with a maximum at550 m l.

from 1-ethy1-2-methy1-3-pheny1-5-chloro-benzimidazolium ethyl sulfateand 1.1.3-trimethy1- indoline-2-methine-w-aldehyde has the followingformula and sensitizes to 580 ma with a maximum at 550 m Example 39.-Thetrimethinecyanine produced from1-ethyl-2-methyl-3-phenyl-5-chloro-benzimidazolium-ethylsulfate and.N-ethyl-thiazoline- 2-methine-w-aldehyde has the following formula andsensitizes from 450 to 525 III/.0 with a maximum at 503 m and sensitizesto 595 m with a maximum at 562 Example 38.'1l1e trimethinecyam'neproduced Example 40.-The trimethinecyanine produced from1-ethyl-2-methyl-3- (4' -methoxyphenyl) benzimidazolium ethyl sulfateand N-ethyl-thiazoline-Z-methine-w-aldehyde has the following formulaand sensitizes from 450 to 510 m with a maximum at 439 mu.

Example 41.The trimethinecyanine produced from1-ethyl-2-methyl-3-phenyl-5.6-dichlorobenzimidazolium-ethylsulfate andN-ethyl-thiazoline-2-methine-w-aldehyde has the following formula CaHa IEFF-S 7 C1 '-CH=CHCH=JJ and sensitizes from 450 to 530 m with a maximumat 508 mu.

Example 42.The trimethinecyanine produced from1-ethyl-2-methyl-3-phenyl-benzimidazolium ethyl sulfate andN-ethyl-thiazoline-2-methine-w-aldehyde has the following formula andsensitizes from 450 to 510 m with a maximum at 493 m Example 43.Thetrimethinecyanine produced from l-ethyl-2-methyl-3-(4-bromopheny1)-benzimidazolium ethyl sulfate and1.1.3-trimethylindoline-2-methine-w-aldehyde has the following formulaand sensitizes to 560 m l with a maximum at 540 m Example 44.-Thetrimethinecyanine produced from 1-ethyl-2-methyl-3-(4-bromophenyl)-benzimidazolium ethyl sulfate andN-ethyl-thiazoline-2-methine-w-aldehyde has the following formula andsensitizes from 450 to 510 m with a maximum at 493 my.

Example 45.The trirnethinecyanine produced from1-propyl-2-methyl-3-phenyl-6-chloro-benzimidazolium-iodide andN-ethyl-thiazoline-Z- methine-w-aldehyde has the following formula andsensitizes from 450 to 520 m with a maximum at 503 mu.

Example 46'.-The trimethinecyanine produced from1-ethyl-2.5-dimethy1-3-phenyl-benzimidazoline-ethyl-sulfate andN-ethyl-thiazoline-Z- methine-w-aldehyde has the following formula andsensitizes from 450 to 510 m with a maxi mum at 493 m Example 48.-Thetrimethinecyanine produced from l-ethyl-2-methyl-3- (4='-chlorophenyl-)-6- chloro-benzimidazolium ethyl sulfate and 1.1.3- trimethyl indoline 2methine-w-aldehyde has the following formula Cans and sensitizes to 580m with a maximum at 550 m Example 49.-The trimethinecyanine producedfrom l-ethyl-2-methyl-3-phenyl-6-chlorobenzimidazolium ethyl sulfate and1.1.3-trimethy1-6- chloro -indo1ine 2 methine-w-aldehyde has thefollowing formula and sensitizes to 580 ml with a maximum at 550 ma.

Example 50.--The trimethinecyanine produced from 1-ethyl-2-methyl-3-(4'-chlorophenyl-) -6- trifiuoromethyl-benzimidazolium ethyl sulfate and1.1.3 trimethyl-indoline-Z -methine-w-aldeand sensitizes to 580 m with amaximum at 550 m Example 51.The trimethinecyanine produced from 1 ethyl2 methyl-3-aoetoXypropy1-benzimidazolium ethyl sulfate and1.1.3-trimethylindoline-2-methine-w-aldehyde has the following formulaand sensitizes to 550 m with a maximum at 528 mp.

Example 52.The trimethinecyanine produced from 1 ethyl 2methyl-3-aoetoXypropyl-benzimidazolium ethyl sulfate andN-ethyl-thiazoline- 2-methine-w-aldehyde has the following formula andsensitizes from 450 to 510 m with a maximum at 493 ma.

Example 53.The trimethinecyanine produced from1-ethyl-2-methyl-3acetoxypropyl-6-chloro-benzimidazolium ethyl sulfateand 1.1.3.6-

tetramethyl-indoline-2-methine-w-aldehyde has the following formula CHaCaHs and sensitizes to 575 m with a maximum at 540 mu.

Example 54.-The trimethinecyanine produced from1-ethy1-2-methyl-3-acetoxypropy1-6-ch1oro-benzimidazolium-ethyl sulfateand 1.1.3-trimethyl 6 methoxy indoIine-Z-methine-w-aldehyde has thefollowing formula CH3 (fall;

and sensitizes to 585 ml with a maximum at 550 m Example 55.Thetrimethinecyanine produced from 1.2 dimethyl 3acetoxypropyl-G-ohlorobenzimidazolium-methylsulfate andN-ethylthiazoline-Z-methine-(ll-aldehyde has the following formulaC'CIEI=CHCH=(IJ H N N X- z s CH: w w 0.0 0.0m

and sensitizes from 450 to 520 mu with a maximum at 498 m Example 56.Thetrimethinecyanine produced from1-ethyl-2-methyl-3-acet0Xyethyl-6-chlorobenzimidazolium ethyl sulfateand N-ethyl-thiazoline-Z-methine-w-aldehyde has the following formulaand sensitizes from 450 to 520 m with a maximum at 498 m Example 57.-Thetrimethinecyanine produced from1.Z-dimethyl-3-acetoxyethyl-fi-ohloro-benzimidazolium-methylsulfate and.N-ethyl-thiazo- Iine-Z-methine-w-aldehyde has the following formula andsensitizes from 450 to 520 m l with a maximum at 498 m Example 58.--Thetrimethinecyanine produced from 1-ethyl-Z-methyl-B-benzylbenzimidazolium-ethylsulfate and 1.1.B-trimethyl-indoline-2-methinew-aldehyde has the following formula and sensitizes from 450 to520 ml with a maximum at 498 m Example 60.-The trimethinecyanineproduced from 1-ethyl-Z-methyl-3-isobutyl-6-chloro-benzimidazolium ethylsulfate and N-ethyl-thiazo- 1ine-2-methine-w-aldehyde has the followingformula and sensitizes from 450 to 520 m with a maximum at 498 my.

Example 61 .-The trimethinecyanine produced from1.Z-dimethyl-3-isobuty1-fi-chloro-benzimidazolium-methylsulfate andN-ethyl-thiazoline- 2methinewaldehyde has the following formula CHa |C1115 CH2 and sensitizes from 450 to 520 ml with a maximum at 498 mp.

Example 62.-The trimethinecyanine produced from 1 ethyl 2 methyl 3acetoxypropyl-4- chloro-benzimidazolium ethyl sulfate and 1.1.3lrimethyl indoline 2 methine-w-aldehyde has the following formula CH3CzHa l I -CHa N vand sensitizes to 560 mp with a maximum of 630 ma.

Example 63.l-The trimethinecyanine produced from 1.2-dimethyl-3acetoxypropyl 4 chlorobenzimidazolium methylsulfate and Nethylthiazoline-2-methine-w-aldehyde has the following formula andsensitizes from 450 to 510 ml with a maximum at 493 mp.

Example 64.-The trimethinecyanine produced from 1.2-dirnethyl-3acetoxypropyl 6 chlorobenzimidazolium-methyl sulfate and 1.1.3.6-tetramethyl-indo1ine-2-methine-w-aldehyde has the following formula andsensitizes to 575 m with a maximum at 540 ma.

Example 65.-The trimethinecyanine produced from 1.2-dimethyl-3acetoxypropyl benzimidazolium-methylsulfate and N-ethyl-thiazoline-Z-methine-w-aldehyde has the following formula.

and sensitizes from 450 to 520 m with a maximum at 493 mp. V

Example 66.The trimethinecyanine produced from 1.2-dimethyl-3-benzyl6-chloro-benzimid azolium-methylsulfate and N-ethyl-thiazoline-2;-methine-w-aldehycle has the following formula and sensitizes from 450 to525 m with a maximum at 500 m Example 67.The trimethinecyanine producedfrom 1-ethy-2 methyl 3 isobutyl-G-trifiuoromethyl-benzimidazolium ethylsulfate and N- ethyl-thiazoline-Z-methine-w-aldehyde has the followingformula and sensitizes from 450 to 525 mm with a maximum at 500 mExample 68.The trimethinecyanine produced from l-ethyl 2methyl-3-isobutyl-6-trifluoromethyl-benzimidazolium ethyl sulfate and1.1.3- trimethyl-indoline-2-methine-w-aldehyde has the following formulaand sensitizes to 570 m with a maximum at 540 mu.

Example 69.The trimethinecyanine produced from 1.2.3-trimethylbenzimidazolium methyl- 7 sulfate and N-ethyl-thiazoline-2-methine-w-a1-dehyde has the following formula C Ha and sensitizes from 450 to 520 milwith a maximum at 490 I'll 1..

Example 70.--The trimethinecyanine produced from1-ethyl-2.3-dimethyl-benzimidazolium-ethyl-sulfate andN-ethyl-thiazoline-2-methine-waldehyde has the following formula I HzS NA B2 C'-OH=CHCH= and sensitizes from 450 to 520 m with a maximum at 490my.

Est-ample 71 .-The trimethinecyanine produced from 1.2.3-trimethylbenzimidazolium methylsulfate andN-ethyl-benselenazole-2-methine-waldehyde has the following formula CH3C2115 and sensitizes to 580 m with a maximum at 545 mp.

Example 73.-The trimethinecyanine produced from1-ethyl-2-methy1-3-dodecyl 6 chlorobenzimidazolium-ethylsulfate and1.1.3-trimethy1- indoline-Z-methine-w-aldehyde has the following formulaand sensitizes to 570 m with a maximum at 540 m Example 74.Thetrimethinecyanine produced from1.2-dimethyl-3-dodecyl-S-chlorobenzimidazolium-methylsulfate andN-ethyl-benzselenazole-2-methine-w-aldehyde has the following formula ISe l]l c1 5 (L'CH=CHCH=O and sensitizes to 590 m l with a maximum at 560m Example 75.-The trimethinecyanine produced from1.2-dimethyl-3-dodecyl-6-chlorobenzimidazolium-methylsulfate andN-ethyl-thiazoline-2- 15 methine-w-aldehyde has the following formula(13H: H:? 01 c -o H=C HCH=C I (11H; 01TH and sensitizes from 450 to 520m with a maximum at 500 m In the above formulae 3: stands for an alkylsulfate radical such as ethyl or methyl sulfate.

We claim:

1. A trimethinecyanine corresponding with the following general formula:

| r r E CCH=CHCH=O D X I". l.

in which R1 is ethyl, 40

R2 is acetoxyalkyl, X is an acid radical,

Y is a member selected from the group consisting of O, S, Se, and

D is an o-phenylene radical,

E is a member selected from the group consisting ofCH2CH2-, ano-phenylene radical, and an o-naphthylene radical,

2. A trimethinecyanine corresponding with the following formula:

in which X is an acid radical.

3. A trimethinecyanine corresponding with the following formula:

in which X is an acid radical.

GUSTAV WILMANNS. OSKAR RIESTER. KARL KUMETAT.

Certificate of Correction Patent No. 2,289,300. July 7, 1942.

GUSTAV WILMANN S ET AL.

It is hereby certified that errors appear in the printed specificationof the above numbered patent requiring correction as follows: Page 1,second column, line 44, after the Word ammonia strike out emulsion; sameline, after finished insert emulsion; page 6, first column, lines 19 and20, for maximum at 439 my read maximum at 493 my; page 8, second column,lines 33 and 34, for of 630 my read at 580 my; and that the said LettersPatent should be read with these corrections therein that the same mayconform to the record of the case in the Patent Office.

Signed and sealed this 30th day of March, A. D. 1943.

[SEAL] HENRY VAN ARSDALE,

Acting Commissioner of Patents.

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